Cathode construction and lamp embodying the same



y 22, 1941- 2 J. ATLEE 2,250,323

CATHQDE CONSTRUCTION AND LAMP EMBODYING THE SAME Filed May e,- 1939 2 Sheets$heet 1 -1 I i3 31 J5 37-35 95 95 J5 July 22, 1941. T E 2,250,323

CATHODE CONSTRUCTION AND LAMP EMBODYING THE SAME Filed May 6, 1939 v 2 Sheets-Sheet 2 INVENTOR Zed fat/e6 @ya rm ATTORNEYO.

Patented July 22, 1941 CATHODE CONSTRUCTION AND LAMP EMBODYING THE SAME Zed J. Atlee, Elmhurst, Ill., assignor to General Electric X-Ray Corporation, Chicago, 111., a corporation of New York Application May 6, 1939, Serial No. 272,222

6 Claims.

My invention relates in general to electronics, and has more particular reference to X-ray generators.

An important object of the invention is to provide means for cooling cathode structures and more particularly the cathode of an X-ray generator.

' Another important object resides in providing a cathode structure having heat transmitting means conductively connected with the cathode and extending outwardly of a sealed envelope in which the cathode may be mounted for operation for the purpose of cooling the cathode by dissipating heat therefrom outwardly of the enclosing envelope as to a bath of oil or other liquid in which the device may be immersed.

Another important object resides in providing an improved means for mounting and supporting the cathode structure in its enclosing envelope; a still further object being to utilize the cathode mounting as heat conducting means for transferring heat from within the envelope outwardly thereof.

Another important object resides in utilizing the cathode mounting as an envelope seal; a still further object being in this respect to simplify the cathode and its mounting and the cathode seal in devices of the character mentioned.

Another important object resides in providing improved and simplified cathode connections for electrically connecting the electron emitting cathode elements with an external source of electrical power for energizing the same.

Another important object is to provide an improved extensible cathode connection adapted to accommodate for expansion due to development of heat at the cathode; a further object being to provide asimplified clamp for making cathode connections in the restricted space available for the purpose.

Another important object is to provide simplified and improved means for supporting electron emitting elements precisely in position in a cathode structure, the same being of importance where the cathode structure is of the focusing type.

respect to the member, and in utilizing said support member as a seal by forming thereon an annular rim forming sealed connection with the enclosing envelope whereby the support member is exposed both inwardly of the envelope and in heat exchange relationship with respect to the cathode structure, and outwardly of said envelope to provide for rapid heat transfer through the member outwardly of the envelope.

These and numerous other important objects, advantages, and inherent functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings,

Figure l is a sectional View taken through an Y-ray generator embodying my present invention;

Figure 2 is an enlarged sectional View taken substantially along the line 2-2 in Figure 1; I

Figure 3 is a sectional view taken substantially along the line 33 in Figure 2;

Figure 4 is a perspective view of parts forming a simplified conductor clamp embodying my present invention;

Figure 5 is an enlarged sectional view, similar to the view shown in Figure 2, illustrating a modified cathode structure embodying the present invention;

Figure 6 is a sectional view taken substantially along the line 6-6 in Figure 5;

Figure 7 is a sectional view taken substantially along the line l! in Figure 6; and

Figure 8 is an enlarged perspective view of a part of a clamp for supporting the electron emitting elements in cathodes constructed in accordance with the teachings of my present invention.

To illustrate my invention I have shown on the drawings an X-ray generator ll comprising spaced-apart anode and cathode means I3 and I5 sealed in an enclosing, preferably glass, envelope l1.

The anode l3 may be of any suitable orpreferred construction, suitably mounted in the envelope I1 and sealed therein, preferably at one end thereof. The cathode l5 likewise is sealed in the envelope, preferably at the end thereof opposite from the anode.

An X-ray generator is conditioned for operation by exhausting from the envelope substantially all gaseous and other impurities therein, the same being accomplished by evacuating the envelope as by means of a molecular exhaust pump and by heating the elements of the generator to a high temperature in order to drive out all occluded gases, the envelope finally being sealed after substantially all impurities have thus been eliminated.

It should be understood that X-ray generators function to produce X-rays in response to the activation of the anode by electronic action established by the operation of the cathode I5, said action consisting of the impingement of electrons emitted by the cathode upon the anode target.

During the operation of the X-ray generator a considerable amount of heat is developed at the cathode, and it is an important, if not the principal object of my present invention to provide means for cooling the cathode structure by dissipating heat therefrom outwardly of the envelope I! through an improved heat dissipating seal comprising means 19 of heat conducting material forming a support for the cathode structure whereby to carry the same in position sealed within the envelope, said means being formed also with a rim 2! having a relatively sharp edge 23 adapted to form a glass-to-metal seal with a sleeve-like reentrant envelope portion 25 formed at the cathode end of the envelope.

The cathode structure may comprise a head 21 which may be formed with one or more cupshaped cavities 29 facing toward the anode, in the bottoms of which cavities are positioned electron emitting elements comprising filaments 3!. The head 21 is fastened rigidly upon the support means l9 in a manner affording a heat conducting path or paths between the head 2'! and the support means [9, and since the support means [9 is exposed outwardly of the envelope H in the cavity defined within the reentrant walls 25, it will be seen that a free and unrestricted heat dispersive path is provided between the head 21 of the cathode structure and the external circuma-mbient medium immediately surrounding the envelope.

In service, X-ray generators may be immersed in oil or other insulating liquid, which, of course, may enter the space within the sleeve-like envelope portions 25 in direct contact with the cathode support means 19, and thus carry off the heat conducted from the cathode and liberated at the outwardly exposed portions of the support means l9, thereby cooling the cathode. The support means [9 also preferably carries a stem means 34 fixed thereon and extending outwardly I thereof within the space defined by the reentrant envelope portions 25.

Where the cathode structure is relatively massive and ponderous, as in the embodiment illustrated in Figure 2, the means i9 may comprise a plate 33, and the cathode structure may comprise an annular wall '35 formed integrally on the head 21 and forming means for connecting the head on the plate 33 as by fastening the walls 35 at the marginal edges of the plate 33 as by means of the bolts 31 or other suitable fastening means.

The plate 33 also may carry the annular rim 2! formed as a separate element and sealingly secured on the plate 33, as at 35, and the stem means 34 comprises a rod 38 supported on the plate 33 in position extending outwardly thereof.

In relatively lighter cathode structures, as shown in Figure 5, the means [9 may comprise simply asheet metalcup-shaped element 36, the marginal Walls of which form the rim 2| and the bottom of which affords a mounting for the head 21, which may be secured on said bottom in any convenient fashion, and preferably by means of a stem 39 having a portion extending between the means l9 and the head 21, and threaded or otherwise secured as at 4| in a cavity formed in the underside of the head 21. The stem 39 also may have an extension 43 extending through and sealed in a central perforation formed in the bottom of the cup-shaped member 36, said extension 43 forming the stem means 34.

The elements 3| comprise filaments accurately positioned in the bottom of the depressions 29, said filaments being mounted and electrically connected at opposite ends on support stems 45. If desired, the filament means 3| may be electrically connected on the head 21, in which case electrical connection between the grounded filament portion and an external power source may be had through the stem means 34. However, at least one of the mounting stems 45 of each filament is supported in position insulated from the head by suitable insulated clamp means 49, preferably carried on the back of the head 21, the mounting stems being supported in position extending through openings 41 formed in the head 2'! and connecting with the bottoms of the cavities 29.

As shown in Figure 2 of the drawings, both of the stems 45 carrying the single filament 3| extend through an opening 41, the members 45 extending within the space defined by the annular wall between the head 21 and the plate 33.

In the embodiment illustrated in Figure 5 wherein a pair of filaments 3| are shown, each disposed in its separate depression 29, said depressions being of elongated slot-like form, one of the support members of each filament is rigidly secured in an opening 5| formed in the head 21 whereby one end of each of the filaments is electrically connected with the head. The other filament support member 45 of each of the filaments extends through an opening 41 connecting an end of the depression 29 with the underside of the head 21. The filament supports which extend in the channels 4'! are supported in the clamps 49.

The clamps 49 comprise each a pair of bracket members, as illustrated in Figure 8, having portions adapted to be secured upon the underside of the head 21, the brackets having platelike portions 51 provided with a pair of spacedapart openings 59, and the spaced brackets of each clamp are arranged so that the portions 51 thereof may receive therebetween two or more clamping blocks 61 of suitable insulating material such as porcelain. These blocks 61 are arranged to clampingly secure therebetween the filament supports 45 whereby the same are rigidly secured on the head in position extending in and through the openings 49; and the blocks 5! are maintained in clamped relationship by means of clamping screws 63 which extend in the openings 59 of the heads of the brackets 54.

The members 45 preferably comprise relatively rigid wires forming conductors, the ends of which wires are spread apart as at 65 adjacent the clamping blocks 6| in order to facilitate connection with conductor means 56 extending through and sealed in openings formed in the support means i9 and by means of which the insulated filament supporting stems may be connected with an external power source. The conductor means 56 comprises flexible conductors 6'! adapted to be connected with the filament supports 45 within the cathode structure, conductor stems 8| extending through and sealed in openings 18 in the support means I9, and conductors 89 outwardly of the means 19, the conductors 61 and 89 being butt-welded to the opposite ends of the stems 8|.

In order to provide simple, inexpensive, and readily applicable means to connect the flexible conductors 61 with the members 45, I provide clamps 69 of simplified construction, the same preferably comprising each a rectangular block ll formed with a channel 13 extending between the opposed lateral sides of the block and into which channel 13 the ends of the members 45 and 61 may be received. The block H also is drilled longitudinally to form a threaded opening 15 connected at one end with the channel 13 and opening at the other end upon an end of the block H.

I provide a set screw, ll adapted to thread into the channel 15 and clamp the conductors 45 and 61 together in the channel 13. The block H and the set screw H are preferably formed of cold drawn steel, and the parts may be formed inexpensively on a screw machine. After the clamps have been applied, I find that under the heat to which they are subjected, the screw Tl becomes frozen in the block H in clamping position, and thus eliminates any possibility of loose connections between the conductors 45 and the flexible connectors G1.

The flexible connectors 61 and 89 preferably comprise stranded Callite upon the ends or which are brazed preferably nickel ferrules '69, which in turn are butt-welded upon the opposite sides of the stems 8i. These stems 8| preferably comprise Fernico alloy and extend through seals 63 formed in the support means 19, said seals comprising Fernico sleeve 85 sealed in the openings 18 and through which openings and sleeves the rods BI extend, the rods 8i being sealed in said sleeves 85 in position insulated therefrom and from the support means I9 by glass sealing globules Bl. Otwardly of said globules 31 the conductors 89 extend to and are electrically connected with terminals 9| on a panel 93 carried on the outwardly extending stem means 34, whereby the filaments 3| may be electrically connected with a source of external electrical power.

In making the assembly the conductors 6T, 8!, and 89 are connected together and sealed in the means I9, the elements 31 are mounted in the clamps 49 and 53 and assembled in the head 21, which is then attached on the support l9, after which the clamps 69 are applied, the clamps in the embodiment illustrated in the Figure 2 of the drawings being applied through openings 93 formed in the annular walls 35 to facilitate this operation and also to reduce the weight of the cathode structure.

The head 21 also is formed with an annular 1 seat 95 to receive skirt means 5? comprising a cylindrical shell or a plurality of curved plates adapted to be attached at one end on the head as by means of the fastening screws 99 in position enclosing the cathode structure and overlying the glass-to-metal seal at 28 in order to protect the same from impingement by stray electrons in the envelope ll during the operation of the X-ray generator.

It will be seen that the arrangements herein described provide simplified cathode constructions each affording a direct heat conduction path from the cathode head 21 through the means [9 whereby the cathode may be cooled by rapid heat dissipation outwardly of the envelope.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in 75 the form, construction, and arrangement of the several parts without departing from the spirit and scopeof the invention, nor sacrificing its attendant advantages, the form herein disclosed being merely for the purpose of demonstrating the invention.

The invention is hereby claimed as follows:

1. In a device of the class described, comprising a sealed envelope and an electrode element supported within said envelope, the combination, with said envelope and element, of mounting means for the element, comprising a plate of heat conducting material having edge portions sealed to said envelope at an opening therein in position exposing one side of said plate outwardly of said envelope through said opening for heat dissipation, means supporting said element on said plate in position within said envelope, comprising a head carrying said element and formed with a frame portion of massive sectional area, means to secure the frame portion on said plate in heat exchange relationship therewith, whereby to provide a heat conducting path from said head to said plate, conductor means electrically connected to said element and extending outwardly of said element through a duct in said plate, and seal means at said duct hermetically sealing the same and insulating the conductor means from the plate, said electrode element comprising a mounting stem rigidly supported on the head and said conductor means comprising a flexible cable and a clamp for securing the cable on the stem Within said frame portion, said frame portion having an opening therein giving access to said clamp.

2. In a device of the class described, comprising a sealed envelope and an electrode element supported within said envelope, the combination, with said envelope and element, of mounting means for the element, comprising a plate of heat conducting material having edge portions sealed to said envelope at an opening therein in position exposing one side of said plate outwardly of said envelope through said opening for heat dissipation, means supporting said element on said plate in position within said envelope, comprising a separately formed heat conducting member providing a head carrying said element, means secured on and in heat exchange relationship with respect to the plate and head for supporting the head in spaced relationship with respect to the plate, conductor means electrically connected to said element and extending outwardly of said envelope through a duct in said plate, and seal means at said duct hermetically sealing the same and insulating the conductor means from the plate, said electrode element comprising a mounting stem rigidly supported on the head and said conductor means comprising a flexible cable, and a clamp for securing the flexible cable on said stem, said clamp comprising a block of material formed with a clamping channel, to receive the stem and cable, and an intersecting channel, a clamp member adapted for assembly in said intersecting channel in position to clamp the stem and cable in the clamping channel, said block and clamp member being of material adapted to weld together at the temperature to which. exposed during the operation of the device. 3. In a device of the class described, comprismg a sealed envelope and an electrode element supported within said envelope, the combination, with said envelope and element, of mounting means for the element, comprising a plate of heat conducting material having edge portions sealed to said envelope at an opening therein in position exposing one side of said plate outwardly of said envelope through said opening for heat dissipation, means supporting said element on said plate in position within said envelope, comprising a separately formed heat conducting member providing a head carrying said element, means secured on and in heat exchange relationship with respect to the plate and head for supporting the head in spaced relationship with respect to the plate, conductor means electrically connected to said element and extending outwardly of said envelope through a duct in said plate, seal means at said duct hermetically sealing the same and insulating the conductor means from the plate, and a sleeve removably secured on said head and extending thence in position enclosing said plate and the envelope sealed portions thereof, as well as the space between the plate and head, to protect the enclosed portions against stray electron impingement.

4.111 a device of the class described, comprising a sealed envelope and an electrode element supported Within said envelope, the combination, with said envelope and element, of mounting means for the element, comprising a plate of heat conducting material having edge portions sealed to said envelope at an opening therein in position exposing one side of said plate outwardly of said envelope through said opening for heat dissipation, means supporting said element on said plate in position within said envelope, comprising a member providing a head formed with a channel therethrough, heat conducting means securing the head in spaced relation with respect to the plate, said electrode element comprising a filament and a pair of mounting stems, one stem being secured to and electrically connected with the head, and the other extending in said channel and being rigidly supported on and insulated from the head.

5. In a device of the class described, comprising a sealed envelope and an electrode element supported within said envelope, the combination, with said envelope and element, of mounting means for the element, comprising a head formed with a channel therethrough and supported on, in position extending within, said element, said electrode element comprising a filament and a pair of mounting stems, one stern being secured to and electrically connected with the head, and the other extending in said channel and being rigidly supported on and insulated from the head.

6. In a device of the class described, comprising a sea-led envelope and an electrode element supported within said envelope, the combination, with said envelope and element, of mounting means for the element comprising a mounting stern supported by said envelope and carrying said element, conductor means extending outwardly of said envelope through a seal, and a clamp for electrically connecting the conductor means with said stem, comprising a block of material formed with a clamping channel, to receive the stem and conductor means, and an intersecting channel, and a clamp member adapted for assembly in said intersecting channel in position to clamp the stem and conductor means in the clamping channel, said block and clamp member being of material adapted to weld together at the temperature to which exposed during the operation of the device.

ZED J. A'I'LEE. 

